The present invention relates to a composition for use in a washing machine and to a process for the use thereof.
Although modern washing machines usually have numerous different washing programs, which differ with respect to the duration and temperature of the individual washing and rinsing cycles, all washing programs essentially comprise the following basic steps: prewashing cycle, main washing cycle, several rinsing cycles and spinning cycle. Whilst the actual detergent which is intended to give rise to the cleaning action is added at the start of the main washing cycle (or optionally at the start of the prewashing cycle), during the rinsing cycles special agents with different functions can be used. These special agents for the rinsing cycles are intended to mainly bring about further advantages for the washing treatment. A non-exhaustive list of such agents and without restriction thereto comprises fragrances (pleasant smell of the washing), fabric softeners (softness of the washing), antistatic agents (reduction or prevention of the build-up of static electricity in the washing), agents for restoring the capacity of the washing to absorb moisture, mild acids (breaking down incrustations or neutralization of alkalinity), bleaches, either having an oxygen or a chlorine base (improving the cleaning action), disinfectants, agents for a persistent protection of both the washing and the person wearing the latter against insects or mites, agents for an improved removal of grease marks, finishing agents giving a protection against creasing, optical brighteners, ironing auxiliaries (to facilitate ironing of the washing), agents for inhibiting dye transfer, enzymes such as cellulases, lipases, etc. for special uses.
The described different functionalities have hitherto been achieved (if at all) by charging different products, partly via separate dosing or charging devices, as well as charging at different times.
The aim of the present invention was to combine within a single product the cleaning function and the function or functions of the substance or substances to be added during the rinsing cycles, with a constant efficiency compared with the results achievable with a separate dosing or charging, or to permit the charging of further substances in the rinsing cycles.
DE-OS 20 65 153 and DE-OS 20 07 413 disclose detergent pellets for use as washing agents, in which it is inter alia provided to combine two components with different functionalities. The structure is formed from a covering or enveloping shell, which is e.g. formed from two shell halves, which comprise a cleaning agent, and a cavity surrounded by the shells and which contains additives such as softeners, brighteners, etc.
British patent 1 390 503 discloses a liquid cleaning agent or detergent which contains capsules, which are insoluble in the composition, but release their content when the composition is diluted with water. This objective is achieved in that the capsules are coated with a substance, which has a poor solubility in water solutions with a high ionic strength, but which is soluble if the ionic strength is reduced by dilution. It is pointed out that this procedure can be used in order to incorporate materials into the liquid cleaning agent, which in the latter are unstable or would produce an instability if added directly. It is also proposed to use this procedure for delaying the release of a specific substance. Reference is made to use in detergents. The encapsulated material is released within two minutes following the dilution of the cleaning agent with water, i.e. during the main washing cycle.
U.S. Pat. No. 4,082,678 describes a fabric conditioner, which comprises a closed container containing a releasable agent and which is used for making water-insoluble or non-dispersible an inner container located in the first container and which is normally water-soluble or water-dispersible, the inner container containing a fabric conditioner. The inner container comprises a substance, whose solubility in water is highly dependent on the ionic strength or the pH-value of the medium and the agent used for rendering the inner container insoluble is an agent for controlling the pH-value or the ionic strength.
Japanese patent applications KOKAI 60-141705, 61-28440, 61-28441, 61-28596, 61-28597 and 61-28598 describe processes for the production of pH-sensitive microcapsules for use in detergents. The pH-sensitive coating is a copolymer of the following monomers:
A) at least one basic monomer of formula I: 
xe2x80x83in which R is hydrogen or a methyl group and R1 and R2 in each case an alkyl group with 1 to 3 carbon atoms and x is an integer from 1 to 4,
B) at least one monomer which is insoluble or difficultly soluble in water and
C) at least one water-soluble monomer.
It is pointed out that the described polymers are insoluble at a pH-value of 9.5 or higher and are soluble at a pH-value of 8.5 or lower. Different ingredients of cleaning agent compositions are described, which can be successfully and usefully coated with the described polymers. The aim of the invention described therein is to protect substances, which only evolve their function during the rinsing process up to the start of the latter and then to release them as immediately as possible. A disadvantage of the solution described in these Japanese patent applications is that the enveloped particles are in direct contact with non-alkaline washing water at the start of the washing cycle, which can give rise to a partial dissolving of the protective covering.
Japanese patent KOKAI 50-77406 discloses a washing aid, which is surrounded by a water-soluble covering or envelope, obtained by mixing polyvinyl acetal dialkyl aminoacetate and at least one organic acid, which is solid at room temperature. This protective envelope is intended to protect the washing aid during the main washing cycle and to release it during rinsing cycles. The described compound reacts to the pH-value change between the main washing cycle and the rinsing cycle. Here again the disadvantage exists of a possible partial dissolving of the protective envelope at the start of the washing cycle.
European patent applications EP 284 191 A2 and EP 284 334 A2 disclose a water-soluble polymer film for releasing washing additives during the rinsing cycle of washing machines, remaining intact during the normal washing cycle over a range of typical temperatures and rapidly dissolving during the rinsing cycle. These applications point out that the use of pH-sensitive coatings was admittedly known, but that these films are normally also temperature-sensitive, so that they do not remain reliably stable during the different temperatures of the washing cycle. The solution proposed is a pH-dependent material (which undesirably also has a positive, temperature-dependent dissolving behaviour) which is combined with a material having a negative, temperature-dependent dissolving behaviour. This combination is supposed to guarantee that the coatings do not dissolve at the high temperatures at the start of the washing cycle (in particular the very high temperatures occurring in American machines).
European patent application EP 481 547 A1 discloses multilayer dishwashing machine tablets having a core, a separating layer surrounding the core and an outer layer for the sequential release of the ingredients of the different layers. This tablet is fundamentally intended to solve two problems, namely 1) incompatible materials can be formulated together in a single tablet and released at different times in order to avoid mutual influencing and 2) compositions, which are intended to evolve their functions at different times, can be formulated in a single tablet.
One of the disadvantages of the prior art described in this document is that the only production process described is the successive moulding of the individual layers. This gives rise to the risk that the core or core envelope is deformed, which can firstly lead to damage (and therefore a reduction of the protective action) to the core envelope and secondly (as a function of the core composition) can give rise to a xe2x80x9cbleedingxe2x80x9d of the core into the material of the envelope and the basic composition. In addition, the intimate full-surface contact between the individual layers can lead to reactions occurring in the boundary layers which are undesired, particularly between the envelope and the basic composition.
The second essential disadvantage of the prior art is that for initiating dissolving of the covering layer the temperature is used as the initiating factor, i.e. temperature-sensitive materials are used for the covering material. As the temperature/time pattern in washing machines can differ very considerably as a function of the selected program it would be difficult, if not impossible, to select a material for the covering which is usable for all possible programs of modern washing machines. EP 481 547 A1 admits (p 7, lines 37 to 43) that the choice of the material of the covering layer must take account of equipment and program-specific features. Thus, there is a clear limitation to the practical usability of the products described. The citation makes no mention of a use for washing machines.
PCT application WO 95/29982 discloses a dishwashing agent with a delayed release of a clear rinsing agent in the form of a nonionic surfactant, which together with an inorganic builder salt forms a core particle, which is provided with a wax-like covering in order to ensure the delayed release. This covering is a substance which does not melt at the operating temperatures encountered during the cleaning cycle, but which at alkaline pH-values is so gradually chemically disintegrated that there is still an effective clear rinsing agent quantity present at the end of the main cleaning cycle and is transferred into the rinse clear cycle. The citation makes no mention of a use for washing machines.
A disadvantage of the solution described in this citation is that the covering is rendered soluble by chemical saponification at alkaline pH-values, so that the time at which the clear rinsing substance is released from the core is a function both of the temperature and the length of the main cleaning cycle. The patent application provides no teaching as to how a product is to be formulated with which the clear rinsing agent can be released in the rinsing cycle in all washing programs of any random equipment type. Finally the product is a mixture of granular cleaning agents and granular clear rinsing particles.
In view of the prior art, the problem of the present invention is to provide a composition according to the preamble, which is usable for most washing programs of different washing machine types and in each of the said cases only releases the substance or substances intended to exert their action substantially firstly in the rinsing cycles only in said cycles. The aim is to achieve this without any significant restriction regarding the choice of detergents used, the substance or substances used for the rinsing cycles and other constituents of the composition.
According to the invention this problem is solved by a composition according to the preamble, which is characterized by a basic composition, which essentially evolves its function in the main washing cycle of the washing machine in the form of a tablet, as well as at least one particle with at least one core comprising at least one substance, which evolves its function substantially during the washing machine rinsing cycles and a covering substantially completely surrounding the core or cores comprising at least one compound, whose solubility increases with decreasing concentration of a specific ion in the surrounding medium, the at least one particle being so placed in or on the tablet that the surface of the particle or particles at the most is only partly in direct contact with the surface of the basic composition surrounding the same and the concentration of the specific ion in the local environment of the particle or particles is adequately high up to a substantially complete dissolving of the tablet, in order to present a significant dissolving of the covering or a significant detachment of the covering from the core or cores.
Preferably the or all the particles are received in at least one tablet cavity completely surrounded the basic composition and having a larger volume than the or all the particles received in the particular cavity.
In an alternative the particle or particles are loosely arranged in the interior of the cavity and in another alternative are fixed. In the case of fixing in the interior of the cavity this preferably takes place by an adhesive.
In a particularly preferred embodiment of the invention the cavity is placed substantially centrally in the interior of the tablet.
According to the invention the tablet has a single, substantially spherical cavity, in which is preferably received a single, substantially spherical particle, whose external diameter is smaller than the internal diameter of the cavity.
In an alternative embodiment of the invention the or all the particles are received in at least one cavity of the tablet, which is only partly surrounded by the basic composition.
The cavity is preferably a depression in one of the surfaces of the tablet, in which the particle or particles are at least partly received.
The particle or particles are preferably received in the cavity or depression in such a way that they do not project over the tablet surface or surfaces.
In an embodiment of the invention the cavity or depression has a substantially circular cross-sectional face parallel to one of the surfaces to which it opens or in which it is placed.
According to a special embodiment of the invention the cavity or depression only opens to such an extent towards the surface or surfaces that the particle or particles received therein cannot pass through the opening or openings of the cavity or depression.
Preferably the particle or particles are loosely arranged in the cavity or depression.
It is also possible for the particle or particles to be fixed in the cavity or depression, fixing preferably taking place with an adhesive.
Preferably, according to the invention, the basic composition comprises at least one composition selected from the group comprising a detergent composition, a water softener composition and a washing intensifier composition.
According to the invention, preferably, the covering comprises at least one compound, which at the concentration of the specific ion at the end of the main washing cycle of the washing machine is not or is only slightly soluble and at the concentration of the specific ion in the rinsing cycles has such a sufficient solubility that it is so substantially dissolved in the rinsing cycles or detached from the core or cores that an at least partial escape of the core material into the medium of the rinsing cycles is permitted.
Preferably the solubility of the compound increases with decreasing OHxe2x88x92 ionic concentration and therefore decreasing pH-value in the surrounding medium.
According to a particularly preferred embodiment of the invention the compound has at a pH-value above 10 no or only a limited solubility and at a pH-value below 9 such an adequate solubility that it is so substantially dissolved in the rinsing cycles or is so detached from the core or cores that an at least partial escape of the core material into the medium of the rinsing cycles is permitted.
Preferably this compound comprises a polymer, in particularly preferred manner a pH-sensitive polymer, which comprises at least one repeat unit, which has at least one basic function, which is not part of the backbone chain of the polymer.
In a preferred embodiment the polymer comprises at least one repeat unit, which is based on a compound selected from the group comprising vinyl alcohol derivatives, acrylates or alkyl acrylates having said basic function.
According to a special embodiment of the invention the polymer is a carbohydrate functionalized with said basic function.
The aforementioned basic function is preferably an amine, in particularly preferred manner a secondary or tertiary amine.
According to an alternative the repeat unit is based on a compound having the following formula III: 
in which G is a linking group selected from xe2x80x94COOxe2x80x94, xe2x80x94OCOxe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94NHCOxe2x80x94, xe2x80x94NHCONHxe2x80x94, xe2x80x94NHCOOxe2x80x94, xe2x80x94OCONHxe2x80x94 or xe2x80x94OCOOxe2x80x94, R1 independently of one another being hydrogen or an alkyl group with 1 to 3 carbon atoms, R2 independently of one another hydrogen or an alkyl group with 1 to 5 carbon atoms and x is an integer from 1 to 6.
Preferably the repeat unit is based on a compound with the following formula IV: 
in which R1 independently of one another is hydrogen or an alkyl group with 1 to 3 carbon atoms, R2 independently of one another hydrogen or an alkyl group with 1 to 5 carbon atoms and x is an integer from 1 to 6.
According to another embodiment of the invention the basic function is an imine or a basic, aromatic N-containing group, preferably a pyridine group or an imidazole group.
According to a further embodiment the pH-sensitive polymer is a polymer derived from chitosan.
The invention finally proposes that the compound comprises K-carrageenan.
According to an embodiment of the invention the core or cores comprise at least one material selected from the group consisting of fragrances, fabric softeners, antistatic agents, agents for restoring the capacity of washing to absorb moisture, mild acids, bleaches, disinfectants, agents for persistent protection of both the washing and the person wearing it against insects or mites, agents for the improved removal of grease marks, agents for finishing with protection against creasing, optical brighteners, ironing auxiliaries, agents for inhibiting dye transfers and enzymes.
In an alternative the core or at least part of the cores can be in the form of an encapsulated liquid. In another embodiment the core or at least part of the cores is in solid form.
The invention also relates to a process for performing a washing cycle in a washing machine, in which the composition according to the invention is added at a suitable time during the prewashing cycle or main washing cycle to the medium located in the washing machine.
In a special embodiment of this process for the case that the basic composition in the form of a tablet is unable, following its dissolving in the medium to make available therein a concentration of the specific ion, up to the end of the main washing cycle, which is sufficiently high in order to prevent a substantial dissolving of the covering and a substantial detachment of the covering from the core or cores, said adequate concentration of the specific ion is brought about by the addition of a further composition, such as e.g. a detergent composition, to the medium of the main washing cycle at an appropriate time.
The composition according to the invention is characterized in that it delivers excellent results both in the main washing cycle and in the rinsing cycles of a washing machine. The tablet is dissolved during the main washing cycle and can evolve its corresponding, intended action (cleaning, water softening, washing intensification, etc.). The particle arranged in or on the tablet contains as the core material the substance or substances having to evolve their main function in the rinsing cycles of the washing machine. Said substance or substances are protected by a covering which, at the ionic concentration, e.g. the pH-value, and the temperature of the main washing cycle, is stable and dissolves or is detached either insigificantly or not at all.
Following the main washing cycle and the pumping out of the washing liquor a dilution effect occurs in the rinsing cycles through the repeated entry of fresh water, so that the ionic concentration or pH-value drops significantly. Obviously the actual course of the ionic concentration or pH-profile in the washing cycle of a washing machine is greatly dependent on the composition of the detergent used. The following table 1 shows in exemplified manner a pH-profile measured in the case of a CANDY Activa 80 Plus washing machine, with a 60xc2x0 C. washing program with 3 kg of fabrics having a normal dirtiness level and 3 standard 40 g detergent tablets, as described in detail hereinafter (example 4).
It is clear that throughout the main washing cycle there is a relatively high pH-value of 10.25 to 10.35, which by the fourth rinsing cycle has dropped to 8.50. The solubility of the covering material must consequently be reduce do such an extent at pH-values of preferably below 9 that it rapidly dissolves or is detached and that the effective core material is released into the surrounding medium, i.e. the rinsing water.
Provided that there is to be no charging by special dosing aids able to retain the particles according to the invention, the particles according to the invention must be chosen sufficiently large that they are not discharged to a significant extent during pumping out of the washing machine following the main washing cycle and the first rinsing cycles.
It is important for the solution according to the invention that the surface of the particle at most is in partial direct contact with the surface of the basic composition of the tablet surrounding it. This can take place in ways specifically described and represented in the application, but also in any other way achieving the sought objective. Examples are the loose arrangement of a smaller particle in a larger cavity and fixing a smaller particle in a larger cavity in such a way that there is no or only a partial contact between the particle and the basic composition of the tablet, etc.
Compared with the prior art this constellation offers the advantage that during the production process, e.g. the moulding of the individual constituents taking place in successive steps, a deformation and possibly resulting damage to the core or cores and/or the covering is reliably avoided, because this could give rise to a reduction of the protective action of the core covering. If it is ensured that no pressure is exerted on the particle during any phase of the production process, it is possible to reliably prevent that in the case of specific core compositions there can be a xe2x80x9cbleedingxe2x80x9d thereof into the material of the covering and the basic composition. It can finally be advantageous for specific compositions of the covering or the basic composition to avoid an intimate, full-surface contact, because otherwise undesired reactions could arise in the boundary layers.
The term xe2x80x9clocal environmentxe2x80x9d, as used in connection with the particles according to the invention, indicates the immediate environment of said particles. The ionic concentration in said local environment of the particle is the determinative factor for the stability thereof. With the products according to the invention the ionic concentration in this local environment is determined at least up to a substantially complete dissolving of the tablet by the ions dissolving therefrom. Preferably the origin of the xe2x80x9cspecific ionxe2x80x9d, at least in a first phase following the addition to the water filling of the water tank, is consequently a compound from the basic composition forming the tablet or is produced by it in the surrounding medium. In the most typical case the conventional, basic detergents are OHxe2x88x92 ions, whose concentration can be expressed as a pH-value.
If the basic composition is not constituted by an e.g. basic detergent composition, but instead e.g. by a water softener composition or washing intensifier composition, the protection of the particle covering is possibly only ensured by a sufficiently high ionic concentration in the local environment of the particle until the tablet has completely dissolved, namely in the cases where the basic composition of the tablet is not in a position to provide a sufficiently high ionic concentration in the washing liquor. In such cases the sufficiently high ionic concentration in the washing liquor and consequently also in the local environment of the particle or particles is brought about by dissolving the detergent (or a further special additive).